Nicknamed Raffaello, the module is the second of three planned pressurized containers the Italian Space Agency is building as part of its contribution to the international outpost.

The first module, called Leonardo, arrived at the Florida spaceport last August. Donatello, the third module, is expected to be delivered in 2001. The cylindrical modules are about 21 feet long, 15 feet in diameter and weight nearly 4 1/2 tons. They can carry an additional 10 tons of cargo.

The modules will be carried to the space station inside the space shuttles' cargo bays. Once in orbit, a module can be removed from the shuttle and docked to the space station by a robotic crane.

The module will then remain at the station for astronauts and cosmonauts to use as a storage closet. They will fly stocked with whatever scientific instruments and other equipment are needed at the time.

Once emptied, the modules can be used to return obsolete or broken gear, trash and other items.

Raffello, which was built by Alenia Aerospazio in Turin, Italy, will be outfitted to carry up to 16 racks for experiments and cargo. Boeing, which is providing engineering support to prepare the module, plans to use a newly developed robotic device to install the racks.

The module also will undergo electrical tests to make sure it is compatible with other space station components.

The first two segments of the outpost were launched into orbit last year. The third component, a Russian-built core module that will provide living quarters for the first crews, is scheduled to be launched late this year.